1. Technical Field
The present disclosure relates to a semiconductor memory device, and more particularly, to a fuse box of the semiconductor memory device.
2. Discussion of the Related Art
Semiconductor memory devices can be classified into Random Access Memory (RAM) devices and Read Only Memory (ROM) devices. RAM devices are volatile memory devices where stored data are lost if a power supply is turned off. ROM devices are nonvolatile memory devices where stored data are retained even if a power supply is turned off. RAM devices comprise Dynamic RAM (DRAM) devices, Static RAM (SRAM) devices, etc. ROM devices comprise Programmable ROM (PROM) devices, Erasable PROM (EPROM) devices, Electrically EPROM (EEPROM) devices, flash memory devices, etc. Flash memory devices can be classified into NOR type devices and NAND type devices.
A defective cell which doesn't operate normally may exist on a memory cell array of a semiconductor memory device due to an error during a fabrication process. A semiconductor memory device includes a redundant cell array and a redundant selection circuit for replacing defective cells. Addresses of the defective cells are stored in the redundant selection circuit. When an address is transmitted from an exterior, the redundant selection circuit compares the transmitted address with the stored addresses in the redundant selection circuit. If the transmitted address is identical to one of the stored addresses, identical access is requested to a defective cell, the redundant selection circuit generates a redundant flag signal, and the redundant cell array is selected instead of the defective cell in the memory cell array.
To remove the defective cells from the memorial cell array and to replace them with redundant cells, fuse circuits are provided to route the connection from the defective cells to the redundant cells.
Addresses of defective cells are stored in a fuse box. Each fuse corresponds to an address of a defective memory cell.